Nano Silver Precipitation and pH Suitability

The formation of black precipitate in Personal Care or Pet Care products using Nano Silver is often due to silver reacting with other substances in the formula, leading to the formation of insoluble silver compounds.

Based on the information for some silver nano products, factors that can cause instability and precipitation include:

• Presence of Salts/Electrolytes: Salts or electrolytes, including chelating agents like EDTA, can affect the stability of ionic silver and colloidal silver, causing precipitation. Therefore, using EDTA might not solve the problem and could potentially be a cause of the issue.
• Cationic Surfactants: Avoid using these with certain types of silver nano, especially ionic and colloidal forms.
• Heat: Some types of silver nano are not heat resistant. They should be added in the final step after the product has cooled down.
• Light: Some ionic silver forms are sensitive to light and should be packaged in opaque containers.

Formula Adjustments to Reduce Black Precipitate:

1. Check other components in your formula for salts/electrolytes or cationic surfactants. If present, consider adjusting or avoiding them.
2. Avoid using EDTA or other chelating agents if you are using ionic or colloidal silver.
3. If your production process involves heat, add the silver nano in the final step once the product has cooled.
4. If using ionic silver, package the product in opaque containers to protect it from light.

Suitable pH Range for Nano Silver:

The suitable pH range depends on the type of nano silver used:

• Ionic Silver:
  • Some types are suitable for pH 2-7 (e.g., Silver (2000ppm, Ionic, Colorless Solution, pH 4-6) is suitable for pH 4-6).
  • Some types are suitable for pH 8-12 (e.g., Silver (2000ppm, Ionic, Colorless Solution, pH 10-12) is suitable for pH 10-12).
• Colloidal Silver:
  • Some types are suitable for pH 6-12 (e.g., Nano Silver (2000ppm, Colloidal, Yellow Solution)).
• Nano Silver Powder (Nano Silver 20nm Powder):
  • This form is highly stable and can be dispersed in various products. A specific pH range is not specified as clearly as for the solutions.

Therefore, you should check the specifications of the specific silver nano product you are using to ensure it is used in an appropriate environment (especially pH) and to avoid incompatible ingredients.